PACKAGING

Hand SO-8 THE POWER MANAGEMENT LEADER

By David Jauregui, International INTRODUCTION RECOMMENDED EQUIPTMENT

Hand-soldering SO-8 MOSFETs to a Proper equipment is important for good joints. You’ll (PCB) may cause damage if not done properly. This applica- need a temperature controlled soldering , such as the tion note describes how to properly hand-solder SO-8 devic- Pace ST-20A with a fine point tip (Pace 1/16” es to PCBs. chisel, single point), and low melting-point solder and flux, Kester Sn60Pb40 “44” Rosin Core, or similar. THE SO-8 FOOTPRINT ATTACHING AND SOLDERING An SO-8 MOSFET must be mated to a proper PCB footprint in order to minimize the chances of mechanical failure. In- There are two essential points to ensure reliable results ternational Rectifier’s minimum recommended footprint is and prevent thermal shock: The soldering iron tip tempera- shown below. ture should be about 300ºC, and the tip must not directly touch device . The SO-8 device should first be tack-soldered to the board so that it will stay within the boundaries of its footprint. First, the gate pad on the PCB. Second, align the device to its footprint. Next, heat the joint just enough to re-flow solder between the pad and the gate lead. The tip should be applied to the pad of the footprint when soldering. Feed the solder at the device lead and pad junction. Soldering time should not exceed what is necessary to flow solder into the joint. Sol- der one lead at a time, alternating between drain and source , leaving the gate lead last. Since the gate lead is tack-soldered to the PCB, you must re-solder the gate to the pad properly for a reliable joint. Fi- nally, remove all flux residue with flux remover.

GROUNDING

MOSFETs are sensitive to (ESD). Proper grounding prevents device failure caused by ESD. The workbench, workmats and the soldering equipment must be grounded. Personnel must also be grounded via a grounded wrist strap. The PCB power and bus lines must also be grounded, when no live voltage is present.

For more information in North America call +1 310 252 7105, in Europe call +49 6102 884 311, or visit us at www.irf.com DT99-3 Hand Soldering SO-8 MOSFETs

DE-SOLDERING

If a device must be removed, de-soldering is necessary. A suitable de-soldering tip is the Pace SOIC-8 Surface Mount Removal Tip. However, there is no guarantee that the device will not be destroyed. Reusing the same device is not recom- mended. Avoid over-heating the board to prevent de-laminat- ing the PCB foil traces. Maintaining a clean PCB footprint is important to reduce mechanical failure. Once the device is out, remove excess solder and any leftover residue.

For more information in North America call +1 310 252 7105, in Europe cal l +49 6102 884 311, or visit us at www.irf.com DT99-3